U.S. Pat. No. 8,957,065 discloses a thienopyrimidine compound having an activity of selectively inhibiting the mutant epidermal growth factor receptor tyrosine kinase, represented by the following Formula 1:

Also, the above document discloses a method for preparing the compound of Formula 1. Specifically, as illustrated in Scheme 1 below, the method comprises reacting 2,4-dichlorothieno[3,2-d]pyrimidine of Formula 3 with 3-nitrophenol to prepare the compound of Formula B; reacting the compound of Formula B with 4-(4-methylpiperazin-1-yl)aniline to prepare the compound of Formula C; then reducing the nitro group of the compound of Formula C to prepare the compound of Formula D; and reacting the compound of Formula D with acryloyl chloride to prepare the compound of Formula 1.

However, the synthesis of the compound in accordance with Scheme 1 has several problems, as explained below. In order to remove impurities generated in the step of obtaining the compound of Formula C, a column chromatography purification method was used, but the method is not suitable for industrial production, giving a low yield. Further, an excess amount of iron is required for reducing the nitro group of the compound of Formula C, and the compound of Formula D thus obtained is reacted with acryloyl chloride, which is hard to handle. In addition, the compounds of Formula D and Formula 1 both need to be purified by using a column chromatography, which is difficult to apply to the industrial production.
Thus, the present inventors have accomplished the present invention by developing a novel method for preparing a thienopyrimidine compound, which allows the easy preparation of the compound in an efficient and industrially applicable way.